Embedded Files
Introduction
Introduction
AdvanNet can provide an estimate of tag direction.
Antennas are placed into a virtual line connecting a logical IN and OUT areas.
Tag direction estimates whether a tag moves from IN --> OUT or OUT --> IN.
Tag direction estimate works only in Autonomous modes.
Tag Direction estimation is heavily affected by the following:
Number of tags to be detected
Number of antennas
Environment
Type of tags
Type of products
Etc
Tag Direction uses a generic algorithm based on read data. For the algorithm to work:
AdvanNet version 2.5.2 or higher.
More than one antenna must be used.
The intersection of the antennas radiation pattern should be smaller as possible.
Use Autonomous mode or derived read modes.
Tag Direction estimate requires EPCGen2 (Session 0 and Target A or AB) settings that may have an impact on read rate.
This means Tag Direction estimate may not match good with scenarios were box level or item level is required.
Tag Direction estimate represents a best effort to resolve goods pass direction.
It has proven to be successful in some scenarios and has failed in some others.
Tag Direction estimate is an estimate!
Any system using it must be prepared to manage incorrect values for the pass direction.
The better the system manages error conditions the better a system will be.
Tag Direction estimate is implemented using a general purpose algorithm. That means that every particular scenario will have potential better ways to resolve pass direction.
How it works?
How it works?
Every tag read data is saved into an in-memory buffer. Once the tag is not read any more, a tag direction resolution is taken.
The algorithm works independently per each tag, and we do not provide higher level data.
Once a tag direction resolution is taken, an event is generated. Events include the epc and the direction type
Events can be received by the usual means:
TCP socket 3177
CSV data
Operation
Operation
Requirements
To estimate the tag direction, the following requirements are needed:
AdvanNet version 2.5.2 or higher
The read mode has to be Autonomous, or any read mode that inherits from Autonomous
More than one antenna must be used
The intersection of the antennas radiation pattern should be as small as possible.
Antennas must face inwards and outwards directions. There are two options
There has to be a minimum separation between the antennas in the travel direction.
The distance d depend on the installation: it is generally between 0.5 meters to 1.5 meters.
The antennas have to be a tilted in a way each antenna points to an opposite directions
Configuration
Configuration
Go to read modes tab
1) Enable Generate TAG_DIRECTION events option
In the Advanced JSON conf, it is possible to define some of the algorithms settings:
tag.direction.debug: enables some additional debug messages
tag.direction.minSamples: minimum number of samples required to attempt the tag direction resolution
tag.direction.inactivityPeriod: inactivity period in ms. After an inactivity period without new reads, the tag direction is resolved.
tag.direction.maxTime: maximum time period in seconds. if a tag is read constantly for more than tag.direction.maxTime, an event of type is generated.
A complete JSON may look like
{"tag.direction.debug":false,"tag.direction.minSamples":5,"tag.direction.inactivityPeriod":5000,"tag.direction.maxTime":20}
2) Configure EPCGen2 Session to 0 and EPCGen2 Target to A or AB
Antenna configuration
Add direction orientation to antenna.
The tag direction estimate will work with Autonomous mode only.
Alternatives
Alternatives
As previously said, the used algorithm is very generic, for the cases where the tag direction estimate does not provide good results, it is possible to process raw data to improve results.
The socket 3177 provides real-time raw data that can be post-process in any programming language.
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